Document U.S. Pat. No. 5,824,063 thus describes a unit carrying replacement heart valves, the unit comprising a tubular implant in synthetic material carrying internally a replacement valve in natural material.
Documents U.S. Pat. Nos. 5,855,601 and 5,868,783 describe new heart valve implantation methods, which offer the advantage of avoiding open heart surgery. These methods provide the implantation, by movement through the blood circulation system, of a heart valve replacement unit comprising a radially expandable intra-vascular cylinder carrying a biological valve internally. An inflatable part of a balloon catheter is placed inside the carrier cylinder and the implantation is done by introduction into a vein and movement as far as the failed valve using A catheter. A two dimensional image screen display allows the detection that the carrier cylinder has reached the required position and the cylinder is then dilated by inflating the balloon through the catheter and maintains its expanded shape. The balloon is then deflated and withdrawn with the catheter.
The carrier cylinder presents a sealed casing, which is thus forced against the artery wall, so as to avoid the blood flow bypassing the replacement valve.
However, when the aorta is involved this procedure is not applicable because the coronary arteries open close to the failed native valves, so that the carrier cylinder is likely to block them, provoking the death of the patient.